1. Field of the Invention
This invention relates to an articulable supporting arm for headrests and other devices such as lamps, mirrors and instruments or the like and has particular reference to a unique system for locking the arm at various desired positions of adjustment and releasing for readjustment.
2. Discussion of the Prior Art
Supporting arms for headrests of optometrist's, dentist's or physician's examining chairs and the like are traditionally articulated to facilitate comfortable positioning of the headrest according to the patient's stature and/or disposition of the head desired by the practitioner.
The usual articulation includes linkage between the headrest and chair which requires locking at two or more points when the arm is finally set for use. For one hand operation, this has heretofore required the investment of relatively complex and costly mechanisms including parallelogram-fashioned linkage with brake shoes and drums as in U.S. Pat. No. 3,041,034, for example, or releasably interlocking ratcheting mechanisms as in U.S. Pat. No. 3,761,128.
Alternatives to such mechanical complexity include the provision of a separate tightening screw at each articulation of the support arm, e.g. as in U.S. Pat. No. 3,477,761, which requires the use of two hands for manipulation of the arm. This seriously inhibits the practitioner.
Accordingly, it is, an object of the present invention to provide a support for a headrest or other device which is operable single-handedly and is of uniquely simple and inexpensive construction.
Another object is to provide a novel readily releasable locking system for an articulable headrest supporting arm wherewith a plurality of joints may be simultaneously positively locked and released with one hand.
Still another object is to afford positive locking in such as the aforesaid structure with thumb pressure and ready release by closing of fingers of the same hand, both operations being performable from a single position of the hand upon the headrest supporting arm.